A modern wireless communication network combines a radio access network (“RAN”) with an Internet Protocol (“IP”) network. The RAN is configured to provide a mobile device with a wireless connectivity over an air-link network, and the IP network is configured to provide the mobile device with IP connectivity and services. FIG. 1 illustrates an exemplary wireless communication network 100 used by a mobile device to access IP services. The wireless communication network 100 may include a third generation or a fourth generation wireless network.
In either case, wireless communication network 100 includes a mobile device 110 configured to access IP services through a home network 120 and an IP network 130. In one implementation, mobile device 110 includes software that enables mobile device 110 to act as a mobile phone. To this end, mobile device 110 is configured to receive as an input a telephone number associated with a call recipient and in response send, over home network 120 and IP network 130, a request to connect to a mobile device associated with the entered telephone number.
The mobile device 110 may be, for example, a wireless telephone, a personal digital assistant (“PDA”), a messaging device (e.g., a pager), a text messaging or a portable e-mail device (e.g., a Blackberry® or a Sidekick®), a portable music player (e.g., an iPod®) or some other electronic portable messaging, entertainment, organization, or gaming device. Regardless of the particular type of mobile device 110, mobile device 110 includes an interface for receiving, from the user, an input such as, for example, a number associated with another mobile device.
The home network 120 includes a radio access technology that enables mobile device 110 to access IP network 130. In particular, home network 120 includes base stations 122, a home access router (H-AR) 124, and a home agent (HA) 126. The base stations 122 may serve as a hub for radio communications over home network 120 and may support sub-layers of an air-link protocol carried for transmitting and/or receiving data packets to and/or from mobile device 110. The base stations 122 could be using one of several mobile access technologies for allowing mobile device 110 to connect to home access router 124. For example, base stations 122 may be using access technologies such as global system for mobile communications (“GSM”), general packet radio service (“GPRS”), code division multiple access (“CDMA”), ultra mobile broadband (“UMB”), long term evolution (“LTE”), and/or WiMax. The base stations 122, however, are not limited to these technologies.
Regardless of the type of technology used by base stations 122, base stations 122 are configured to allow mobile device 110 to connect to home access router 124. The home access router 124 terminates an interface of mobile device 110 toward home network 120. To this end, home access router 124 performs packet routing and forwarding, provides lawful interception of traffic, and relays traffic between base stations 122 and home agent 126.
The home agent 126 is configured to support an interface to IP network 130. In particular and in one implementation, home agent 126 is configured to allocate an IP address to mobile device 110, provide IP access policy enforcement, perform lawful interception of IP traffic, support billing and charging for IP services, and provide per-user based packet filtering.
The home network 120 also includes a home management entity 128. The home management entity 128 is configured to perform a management function such as authentication, keeping track of a current location of mobile device 110, paging and roaming. The home management entity 128 is also configured to assign IP addresses and provide policy information regarding network communication to mobile device 110.
The wireless communication network 100 supports mobile communications in a limited area based on the coverage area of home network 120. That is, depending on the location of mobile device 110, wireless communication network 100 may not be able to support all calls associated with mobile device 110. When mobile device 110 roams outside the coverage area of home network 120, its signals may be picked up by base stations associated with a visited network (e.g., a roaming network). This scenario is illustrated in more detail with respect to FIG. 2.
FIG. 2 illustrates an exemplary wireless communication network 200 in which a mobile device has roamed outside the coverage area its home network and into a coverage area of a visited network. The wireless communication network 200 includes mobile devices 210, 212, a home network 220, an IP network 230, and a visited network 240. The mobile device 210, home network 220, and IP network 230 are generally similar to mobile device 110, home network 120, and IP network 130 and therefore are not described in more detail.
The visited network 240 includes features similar to home network 220. In particular, visited network 240 includes base stations 242, a roaming access router (R-AR) 244, and a roaming home agent (R-HA) 246. The base stations 242, roaming access router 244, and roaming home agent 246 are generally similar to base stations 122, home access router 124, and home agent 126. Accordingly, these items are not described in more detail.
The wireless communication network 200 illustrates a scenario in which a user of mobile device 210 roams outside its home network 220 (e.g., San Francisco, Calif.) into a visited network 240 (e.g., Washington D.C.), and the user of mobile device 210 makes a telephone call, for example, to another user operating mobile device 212 inside Washington D.C. As shown, the traffic associated with the telephone call goes away from Washington D.C. to San Francisco, Calif. via communication session 250 and comes back to Washington D.C. via the same communication session. The policies hosted by the roaming access router dictates the destination of the traffic. According to a standard policy, roaming access router 244 is configured to send traffic associated with mobile device 212 to San Francisco. To illustrate further, in one example, as a part of authenticating the mobile device 212 and the establishing communication session 250, roaming access router 244 receives a list of source addresses that should be routed to San Francisco. Among the source addresses is the source address employed by mobile device 212. Therefore, when roaming access router 244 receives the traffic having a source address employed by mobile device 212, roaming access router 244 forwards this traffic to San Francisco through communication session 250. The traffic then comes back from San Francisco to Washington D.C. through the same communication session.
As one can imagine, in some implementations, sending the traffic from Washington D.C. to San Francisco, Calif. and back to Washington D.C. may not provide for a minimized latency and the best route optimization. Additionally, sending the traffic in this manner may not provide for optimum traffic quality because the greater communication path results in a greater degradation of voice quality.
Accordingly, one of the features not defined in the prior art is how to optimize traffic routing when a mobile device roams outside its home network. Therefore, there is a need for a route optimization method that enables a mobile device to selectively route traffic within a visited network without having to send the traffic to the home network. This is needed to insure a desired quality of service.